In coating systems of the type stated at the beginning that are known from the market, the application device, which can be a high-speed rotating atomizer or a spray gun in paint processes, for example, is supplied with liquid materials. On the one hand, these can be liquid coating materials, in particular paints, which are applied to an object to be coated.
On the other hand, solvents, flushing agents or release agents also flow through the flow path to the application device and are also delivered by this if applicable. For example, in the case of a material change, the conduits and lines carrying the material must be cleaned of the paint used previously, to which end a flushing agent is conveyed through the relevant conduits and lines. For instance, in the case of a paint shop, a change device is used for coating materials for such a material change, i.e. a colour change device, if it occurs frequently in normal operation that for coating an object a paint is to be used other than the paint with which a preceding object was painted.
To keep paint losses and the amounts of flushing agent required to a minimum, so-called pigging technology is often used, in which the coating materials or the flushing agent is pushed through the conduits and lines with the aid of pigs. In this case the pig is moved back and forth between two pigging stations, one of which is arranged close to the application device and the other close to the change device.
In addition to paints, other coating materials can be applied with different application devices, for example preservatives such as waxes, individual components of multicomponent adhesives or if applicable even highly viscous substances such as sealants.
Without further measures the liquid materials are conducted through the flow path at a temperature that corresponds to the ambient temperature or the temperature at which the materials were introduced into the line system. Paints in particular, but also flushing agents, are normally kept in a paint supply room in containers and are brought there to a set temperature, which should as far as possible exist also upon delivery of the material by the application device, before the materials are introduced into the line system. To this end the material is heated or cooled depending on its starting temperature and the desired target temperature.
On its path through the line system to the application device, however, the temperature of the material can change under the influence of the ambient temperature. Moreover, a usage temperature of the materials that is higher or lower than the ambient temperature can lead to positive effects in different application or operating processes. Thus most normal flushing agents can take up more contaminants at higher temperatures than is possible at a comparatively lower temperature. An increased or reduced temperature compared with the ambient temperature can be desirable for the coating materials too.